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From: tromp@piring.cwi.nl (John Tromp)
Newsgroups: comp.lang.c
Subject: Re: swap(x,y)
Message-ID: <8350@boring.cwi.nl>
Date: 22 Aug 89 08:21:03 GMT
References: <MYwDEFy00WB842JEUx@andrew.cmu.edu>
Sender: news@cwi.nl
Lines: 25

tg1e+@andrew.cmu.edu (Timothy R. Gottschalk) writes:


>       To swap two variables x,y in C without using a temporary variable:

>       /* begin swap */
>       x += y;
>       y = x - y;
>       x -= y;
>       /* end swap */

>       Just curious...(this looks pretty valid) does anyone know an even
>simpler method?  I would never program this way -- it's more of a theory
>question.  I've been told that it can't be done (???).
>Tim Gottschalk
>Pgh, PA

How about

x^=y^=x^=y;

Avoids possible overflow problems and looks great in an
Obfuscated C Code entry too!

John Tromp (tromp@cwi.nl)